1. Field of the Invention
The present invention relates to a method of measuring texture in metal plates or sheets, and particularly, pertains to a method of utilizing ultrasound to measure texture. The invention also pertains to a method for the prediction of mechanical formability of metal plates using ultrasound.
2. Problems in the Art
It would be greatly advantageous to be able to quickly and accurately discern texture in relatively thin plate and sheet material during its production. With such information, the manufacturing process could be efficiently controlled to produce a product of desired texture characteristics, or to correct texture deficiencies within a short time of when they occur. Knowledge of this texture is important, for example, in predicting the capability of the metal to be formed into parts of complex shape.
Previously, texture analysis required periodic sampling of the continuously produced sheet or plate material, and then utilization of x-ray or neutron diffraction techniques. Not only does this require destructive analysis from the periodically excised samples, such processes are time consuming and therefore cannot be used to immediately correct or change the production processes. Furthermore, x-ray processes give data only regarding the near surface of the material. Even though the material being analyzed is relatively thin sheet or plate, the texture characteristics can change drastically through its cross-section. The neutron processes provide information about the entire thickness of the material. However, the samples must be taken to a neutron source to perform the analysis. Therefore, the accuracy of these currently used processes is not as reliable or convenient as is desired.
Therefore, a real need exists for improvement regarding the monitoring and estimation of texture in sheet or plate materials such as rolled metal plate. It has previously been known that certain properties and inferences of texture can be derived from the analysis of received ultrasonic energy after it has been passed through the material. In particular, it has been discovered that texture might be inferred from measuring the differences in speed of ultrasonic energy in different directions through the material.
However, this knowledge has applied to thick metal pieces in which the wave properties are uninfluenced by the part surfaces. They must be modified to be applied to metal plates and sheets, which is the geometry often encountered when one wishes to control texture.
The present inventors have worked with theoretical foundation for such non-destructive texture estimation. However up until the present invention, the theoretical bases for valid and accurate texture estimation had not been discovered. In fact, previous published works on the matter had been incorrect in the assumptions and theory for certain parts of the analysis.
It is therefore a principal object of the present invention to improve over or solve the deficiencies and problems in the art.
Another object of the present invention is to provide a method of ultrasonic measurement of texture which provides efficient and accurate estimates of texture in plate or sheet material.
A further object of the present invention is to provide a method as above described which is non-destructive to the material being analyzed.
Another object of the present invention is to provide a method as above described which can be easily adapted to be used in the area of and during production of the material.
Another object of the present invention is to provide a method as above described which does not require complex, time-consuming, or impractical processes or equipment to derive accurate texture estimations.
A further object of the present invention is to provide a method as above described which utilizes ultrasound as an interrogating medium.
These and other objects, features, and advantages of the invention will become more apparent with reference to the accompanying specification and claims.